Oso unvented. Cold water through tundish

[armyash]

Had a customer ask me to look at her unvented cylinder.

Cold water running through tundish. Isolate supply to cylinder and the water stops running, needs new combi valve.

She did have insurance who refused to touch it because it hadn't been serviced for 2 years.

I've advised to change t and p valve and expansion valve also so all the components are new and saves something else going in the near future. Would you say that is good advice? The parts are not cheap, would be direct from manufacturer.

Labour wise I'm thinking 2 hours and will do a service certificate as I go so should she need insurance again she is covered.

 

[Welder]

Had a customer ask me to look at her unvented cylinder.

Cold water running through tundish. Isolate supply to cylinder and the water stops running, needs new combi valve.

She did have insurance who refused to touch it because it hadn't been serviced for 2 years.

I've advised to change t and p valve and expansion valve also so all the components are new and saves something else going in the near future. Would you say that is good advice? The parts are not cheap, would be direct from manufacturer.

Labour wise I'm thinking 2 hours and will do a service certificate as I go so should she need insurance again she is covered.

Hi Ash

So long as you replace the items with those rated exactly the same it does not matter. That said the MI police will be along soon to disagree. I only got told that by the BBA so, hell, what do they know?

Why did you conclude it was the pressure relief valve? Did you disassemble it? Does the T&P not flow into the same tundish? If the T&P is fine there is no need whatsoever to change it.

What's the state of the pressure vessel? Is that pressurised properly? Remember the charge must be appropriate for the main PRV setting.

You're kinda obligated ( as a professional installer) to give her a record. Ask her to keep it by the cylinder. REMEMBER. Get her agreement on doing the service at the same time NEXT YEAR and put it in your diary.
You may wish to disassemble all components you change and then silicone grease all threads and seals. It'll make it a doddle next time no matter how bad they get.

 

[ShaunCorbs]

Are the expansion vessels gone or just flat ?

 

[armyash]

There is no expansion vessel, there is a expansion relief valve.

A company I worked at before used to make us change all components if it looked as though they had not been done for a while, would save getting a call back a few months down the line because a different component had failed and water was running through the tundish again. This may seem a bit over the top but it saves disputes with customers.

 

[ShaunCorbs]

so not like this?

 

[armyash]

Also can anyone recommend an unvented fault finding course. I was taught the following:

If the water running through the tundish is constant and its cold, it's the combi valve.

It's it intermittent and warm its the ex vessel that needs attention.

If it's hot it's the t and p valve.

Not the best training I admit, if I can get on a decent course that would be good. Doing the unvented course to get qualified is one thing but it was all aimed at the set up/install side from what I remember.

 

[armyash]

No it wasn't like that shauncorbs.

 

[chris watkins]

Come on Ash there must be something to accommodate expansion, either it is a bubble top or it has a vessel/s ?
If it hasn't got a vessel did you recharge the bubble, it could be that the expansion relief was discharging because the expansion was not being accommodated.
In which case it just needed a service.

 

[armyash]

so not like this?

Like this.

 

[ShaunCorbs]

internal bubble

 

[Welder]

internal bubble

On an OSO?!?

 

[chris watkins]

1. I would have felt the T&P discharge pipe to see if it was hot, if cylinder is hot then any discharge from it will make the pipework hot.
2. If it is cold then assume the relief is discharging.
3. Checked the expansion vessel & drained down & recharged the vessel / bubble.
4. Re-filled the cylinder set it to heat & check for further discharge if none then monitor, if there is then loosen the nut on the discharge side of each to confirm if it is the relief or the T&P replace as required.

 

[Welder]

1. I would have felt the T&P discharge pipe to see if it was hot, if cylinder is hot then any discharge from it will make the pipework hot.
2. If it is cold then assume the relief is discharging.
3. Checked the expansion vessel & drained down & recharged the vessel / bubble.
4. Re-filled the cylinder set it so heat & check for further discharge if none then monitor, if there is then loosen the nut on the discharge side of each to confirm if it is the relief or the T&P replace as required.

Agree. However I always removed the relief valve head and checked the seat just in case running a finger smeared with silicone grease over it so it can never stick (as rubber does when not used frequently) so ends up tearing when it does eventually get lifted off the seat.
BTW, when you do that it always leaks when put back. However by turning it a few times it reseats.
God we're anal!!!

 

[armyash]

If I isolated the inlet but it's the t and p that is faulty would this not continue to run after I have isolated?

 

[chris watkins]

On an OSO?!?

Series 20 & I think 16 are bubbles Dave.

 

[Welder]

Series 20 & I think 16 are bubbles Dave.

Thanks Chris. Gosh never knew that.

 

[armyash]

I have the customers copy of the manual

Come on Ash there must be something to accommodate expansion, either it is a bubble top or it has a vessel/s ?
If it hasn't got a vessel did you recharge the bubble, it could be that the expansion relief was discharging because the expansion was not being accommodated.
In which case it just needed a service.

Has the air gap with the instructions on the side like with the megaflo. Followed that and no change.

 

[Welder]

If I isolated the inlet but it's the t and p that is faulty would this not continue to run after I have isolated?

Depends. As you remove the pressurisation from the incoming side then, if it's borderline on the pressure side, it may sit back down and seal. You could only tell that if you had pressure gauges all over the show.

Did you reset the bubble? How long did that take?

 

[chris watkins]

Thanks Chris. Gosh never knew that.

Thats because you never asked BBA.

Sorry Dave just could not resist that one.

 

[Welder]

Thats because you never asked BBA.

Sorry Dave just could not resist that one.

View attachment 36261

Swine!
Note to self: Watkins dies on Thursday...

 

[armyash]

Depends. As you remove the pressurisation from the incoming side then, if it's borderline on the pressure side, it may sit back down and seal. You could only tell that if you had pressure gauges all over the show.

Did you reset the bubble? How long did that take?

Not long as the customer had done it themselves twice before I got there trying to sort the issue themselves. They said it's been runni g constantly for about 2weeks.

 

[Welder]

Not long as the customer had done it themselves twice before I got there trying to sort the issue themselves. They said it's been runni g constantly for about 2weeks.

TBH, I think you're right. Change the sodding lot and be done with it. You are not going to get paid for being clever & diagnosing in this instance. #Pragmatism.

 

[chris watkins]

I have the customers copy of the manual Has the air gap with the instructions on the side like with the megaflo. Followed that and no change.

& it wasn't coming from the T&P ? Then it was the relief that needed replacing. If the composite (combination) valve set is old, >12 years, I might suggest to customer it is replaced but not the T&P. I am generally against carpet bombing parts on jobs I think it is unprofessional but then occasionally I will get court out.
BTW you shouldn't remove customer copy of MI's. Get yourself an iPAD & download them as required would be my tip.

 

[armyash]

TBH, I think you're right. Change the sodding lot and be done with it. You are not going to get paid for being clever & diagnosing in this instance. #Pragmatism.

I think that's the best thing in this case. I know it's not ideal. Im not making a lot on the job 2hrs labour plus the cost of the parts, will recommission and cover all bases.

There is a doc fitted half way up called a commissioning valve or something I'm going to change that also. Calling her first thing with a price in the morning and will be honest, will say its not worth risking another component going in a few months which is possible if all the same age, will check the whole thing over and issue a service record. Or I'll say I'll change the combi valve only but if water starts discharging again after a month or so from something else its chargeable again.

 

[armyash]

& it wasn't coming from the T&P ? Then it was the relief that needed replacing. If the composite (combination) valve set is old, >12 years, I might suggest to customer it is replaced but not the T&P. I am generally against carpet bombing parts on jobs I think it is unprofessional but then occasionally I will get court out.
BTW you shouldn't remove customer copy of MI's. Get yourself an iPAD & download them as required would be my tip.

Yes I'm sure it's the combi valve. I'm going to give her the option of just changing that or all of it. Last thing I want to do is come across unprofessional but I get what you mean. It looks a case of I'm not sure so I'll change it all. I had to take the instructions as I had poor signal and didn't know if they were available online. Customer was OK with it. I showed her the lever valve to isolate if needed.

 

[markfxy]

I had one recently the prv was running intermitently turns out it was the basin mixer tap the mains pressure was lifting the ceramic disc and pressurising the cylinder I put an nrv on the hot feed to the tap and problem solved.
Took me a while to sus it out though

 

[armyash]

Job done. It was the combi valve. Gave the customer the option to change the t and p also or not she said change it anyway.

Back Wednesday evening to service the boiler too.
Icos